Fire-season weather: what ten summers of data show

By Julia · weather-au.com editorial team · Published 23 October 2026 · 5 min read

This article does not describe any fire. We have no fire records in our data and we will not tell the story of any particular event from memory. What we do have is ten southern summers of daily weather, and weather is the part of a bad fire day that a forecast can see. So the question here is narrower and more useful: how often did the weather ingredients line up, in which city, and in which summer?

Our guide to bushfire weather explains the recipe: dry fuel, low humidity, high temperature, strong wind. We can measure three of the four from the archive. Humidity we did not fetch, so it is missing, and so is the state of the fuel itself. Take everything below as a count of ingredients, not a danger rating. The official ratings come from the Australian Fire Danger Rating System, which uses far more than we do.

Summers run from 1 December to the end of February and are named by the year they end: the summer of 2019–20 is December 2019 to February 2020. We use ten of them, 2015–16 to 2024–25, for Adelaide, Melbourne, Canberra, Perth, Sydney and Hobart.

The rules we used

• Hot: a daily maximum of 35 °C or more.
• Windy: a daily wind gust of 50 km/h or more at 10 m (a model value for a 25 km grid cell, not what a fire front would feel).
• Dry: less than 5 mm of rain in the 14 days before. We chose this ourselves; it is a crude stand-in for dry fuel.

Hot and windy is the first filter. Adding "dry" gives the strictest count.

Ingredient by ingredient

Heat alone is a poor guide. Perth has 127 days at 35 °C or more in ten summers, Adelaide 86, Melbourne 66, Canberra 37, Sydney 32 and Hobart 6. But wind changes the order: Perth still leads with 58 hot and windy days, Melbourne comes second with 45 (it has fewer hot days than Adelaide but more of them with a gust), then Adelaide 34, Sydney 25, Canberra 14 and Hobart 4.

Dryness reshuffles it again. Requiring a dry fortnight beforehand, Perth keeps 54 of its 58, Adelaide 23 of 34, Melbourne 13 of 45, Canberra 5 of 14, and Sydney 1 of 25. Perth's hot and windy days nearly all follow dry weather: its summers are dry by nature (41 mm normal from December to February). Sydney is the opposite: it is hot and windy often enough, but it rains too often in between.

Summer by summer

A few years stand out, and each is a number in the table rather than a story.

• Canberra, 2019–20. Seven hot and windy days, five of them after a dry fortnight, and a run of six days at 35 °C or more from 27 December 2019 to 1 January 2020. Canberra then has none in the next five summers. The longest run of dry days (under 1 mm) was 35 days in that same summer.
• Adelaide, 2018–19. Seven hot and windy days, five after dry weather, and a dry run of 40 days, the longest of any Adelaide summer in the decade.
• Melbourne, 2018–19 and 2024–25. Nine hot and windy days in 2018–19, five of them after a dry fortnight. In 2024–25 there are eleven, the most of any Melbourne summer, but none came after a dry fortnight. Same wind, different fuel.
• Perth, 2019–20 and 2021–22. Twelve and fourteen hot and windy days, all of them after a dry fortnight. Perth's longest dry run was 85 days in 2023–24.

The spring that came before

Fuel depends on what happens before summer. September to November rain, in millimetres:

Canberra's spring of 2019 is the driest of the ten, at 98 mm against a normal of 171 mm (57%). Sydney's spring of 2016 was the driest there, at 115 mm. Adelaide's driest are 2023 and 2024 (91 and 93 mm, against a normal of 124 mm). At the other extreme, spring 2022 brings Melbourne 452 mm, Canberra 370 mm and Adelaide 340 mm, more than double their normals. A wet spring does not rule out a dry summer, though: Adelaide's summer of 2022–23 still has six hot and windy days, five of them after a dry fortnight.

The link between a dry spring and a bad summer is plausible, and it shows in Canberra, but ten summers in six cities cannot prove it.

What this does not tell you

1. No humidity and no fuel moisture. Two of the four ingredients are not in these counts.
2. No wind direction. A change in wind direction is what turns a fire's flank into a front. We cannot see it in daily gusts.
3. A grid cell, not a bush road. Terrain, vegetation and local gusts can all differ from a 25 km average.
4. No tropical north. Darwin and Cairns have their fire season in the dry months from June to October, a different calendar; see the guide.

If you live in or travel through bush country in summer, what matters is the fire danger rating for your district, published by the state fire service the day before, and the advice that goes with it. Our data says when the conditions line up in a given city; the rating says what to do about it.

Period of the data cited: 2015–2025.